was mistaken
Die Ärztin irrte sich in ihrer Diagnose.
The doctor was wrong in her diagnosis.
Der Arzt irrte sich in seiner Diagnose.
The doctor was wrong in his diagnosis.
Sie irrte sich in ihrer Annahme, er sei gekommen, um sie zu sehen.
She was mistaken in her assumption that he had come to see her.
Tom irrte sich, Maria aber hatte recht.
Tom was mistaken, but Maria was right.